AutorÃa | Ultima modificación | Ver Log |
<?php// This file is part of Moodle - http://moodle.org///// Moodle is free software: you can redistribute it and/or modify// it under the terms of the GNU General Public License as published by// the Free Software Foundation, either version 3 of the License, or// (at your option) any later version.//// Moodle is distributed in the hope that it will be useful,// but WITHOUT ANY WARRANTY; without even the implied warranty of// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the// GNU General Public License for more details.//// You should have received a copy of the GNU General Public License// along with Moodle. If not, see <http://www.gnu.org/licenses/>.namespace filter_tex;use core\context\system as context_system;use core\exception\coding_exception;use core\output\actions\popup_action;use core\url;use core_useragent;use stdClass;/*** Moodle - Filter for converting TeX expressions to cached gif images** This Moodle text filter converts TeX expressions delimited* by either $$...$$ or by <tex...>...</tex> tags to gif images using* mimetex.cgi obtained from http: *www.forkosh.com/mimetex.html authored by* John Forkosh john@forkosh.com. Several binaries of this areincluded with* this distribution.* Note that there may be patent restrictions on the production of gif images* in Canada and some parts of Western Europe and Japan until July 2004.** @package filter_tex* @subpackage tex* @copyright 2004 Zbigniew Fiedorowicz fiedorow@math.ohio-state.edu* Originally based on code provided by Bruno Vernier bruno@vsbeducation.ca* @license http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later*/class text_filter extends \core_filters\text_filter {#[\Override]public function filter($text, array $options = []) {global $CFG, $DB;// Do a quick check using stripos to avoid unnecessary work.if ((!preg_match('/<tex/i', $text)) &&(strpos($text, '$$') === false) &&(strpos($text, '\\[') === false) &&(strpos($text, '\\(') === false) &&(!preg_match('/\[tex/i', $text))) {return $text;}$text .= ' ';preg_match_all('/\$(\$\$+?)([^\$])/s', $text, $matches);for ($i = 0; $i < count($matches[0]); $i++) {$replacement = str_replace('$', '$', $matches[1][$i]) . $matches[2][$i];$text = str_replace($matches[0][$i], $replacement, $text);}// The following regular expression matches TeX expressions delimited by:// <tex> TeX expression </tex>// or <tex alt="My alternative text to be used instead of the TeX form"> TeX expression </tex>// or $$ TeX expression $$// or \[ TeX expression \] // original tag of MathType and TeXaide// or [tex] TeX expression [/tex] // somtime it's more comfortable than <tex>.$rules = ['<tex(?:\s+alt=["\'](.*?)["\'])?>(.+?)<\/tex>','\$\$(.+?)\$\$','\\\\\[(.+?)\\\\\]','\\\\\((.+?)\\\\\)','\\[tex\\](.+?)\\[\/tex\\]',];$megarule = '/' . implode('|', $rules) . '/is';preg_match_all($megarule, $text, $matches);for ($i = 0; $i < count($matches[0]); $i++) {$texexp = '';for ($j = 0; $j < count($rules); $j++) {$texexp .= $matches[$j + 2][$i];}$alt = $matches[1][$i];$texexp = str_replace('<nolink>', '', $texexp);$texexp = str_replace('</nolink>', '', $texexp);$texexp = str_replace('<span class="nolink">', '', $texexp);$texexp = str_replace('</span>', '', $texexp);$texexp = preg_replace("/<br[[:space:]]*\/?>/i", '', $texexp);$align = "middle";if (preg_match('/^align=bottom /', $texexp)) {$align = "text-bottom";$texexp = preg_replace('/^align=bottom /', '', $texexp);} else if (preg_match('/^align=top /', $texexp)) {$align = "text-top";$texexp = preg_replace('/^align=top /', '', $texexp);}// Decode entities encoded by editor, luckily there is very little chance of double decoding.$texexp = html_entity_decode($texexp, ENT_QUOTES, 'UTF-8');if ($texexp === '') {continue;}// Sanitize the decoded string, because $this->get_image_markup() injects the final string between script tags.$texexp = clean_param($texexp, PARAM_TEXT);$md5 = md5($texexp);if (!$DB->record_exists("cache_filters", ["filter" => "tex", "md5key" => $md5])) {$texcache = new stdClass();$texcache->filter = 'tex';$texcache->version = 1;$texcache->md5key = $md5;$texcache->rawtext = $texexp;$texcache->timemodified = time();$DB->insert_record("cache_filters", $texcache, false);}$convertformat = get_config('filter_tex', 'convertformat');if ($convertformat == 'svg' && !core_useragent::supports_svg()) {$convertformat = 'png';}$filename = $md5 . ".{$convertformat}";$text = str_replace($matches[0][$i], $this->get_image_markup($filename, $texexp, 0, 0, $align, $alt), $text);}return $text;}/*** Create image link.** @param string $imagefile name of file* @param string $tex TeX notation (html entities already decoded)* @param int $height O means automatic* @param int $width O means automatic* @param string $align* @param string $alt* @return string HTML markup*/protected function get_image_markup(string $imagefile,string $tex,int $height,int $width,string $align,string $alt,): string {global $CFG, $OUTPUT;if (!$imagefile) {throw new coding_exception('Image file argument empty in get_image_markup()');}// Work out any necessary inline style.$rules = [];if ($align !== 'middle') {$rules[] = 'vertical-align:' . $align . ';';}if ($height) {$rules[] = 'height:' . $height . 'px;';}if ($width) {$rules[] = 'width:' . $width . 'px;';}if (!empty($rules)) {$style = ' style="' . implode('', $rules) . '" ';} else {$style = '';}// Prepare the title attribute.// Note that we retain the title tag as TeX format rather than using// the alt text, even if supplied. The alt text is intended for blind// users (to provide a text equivalent to the equation) while the title// is there as a convenience for sighted users who want to see the TeX// code.$title = 'title="' . s($tex) . '"';if ($alt === '') {$alt = s($tex);} else {$alt = s(html_entity_decode($tex, ENT_QUOTES, 'UTF-8'));}// Build the output.$anchorcontents = "<img class=\"texrender\" $title alt=\"$alt\" src=\"";if ($CFG->slasharguments) {// Use this method if possible for better client-side caching.$anchorcontents .= "$CFG->wwwroot/filter/tex/pix.php/$imagefile";} else {$anchorcontents .= "$CFG->wwwroot/filter/tex/pix.php?file=$imagefile";}$anchorcontents .= "\" $style/>";$imagefound = file_exists("$CFG->dataroot/filter/tex/$imagefile");if (!$imagefound && has_capability('moodle/site:config', context_system::instance())) {$link = '/filter/tex/texdebug.php';$action = null;} else {$link = new url('/filter/tex/displaytex.php', ['texexp' => $tex]);$action = new popup_action('click', $link, 'popup', ['width' => 320, 'height' => 240]);}// TODO: the popups do not work when text caching is enabled.$output = $OUTPUT->action_link($link, $anchorcontents, $action, ['title' => 'TeX']);$output = "<span class=\"MathJax_Preview\">$output</span><script type=\"math/tex\">$tex</script>";return $output;}}